The present invention relates to an improved device for continuously coating a carbon fiber fabric or similar with a passivating protective layer based on a carbide.
A process and a device capable of permitting the continuous coating of carbon filament yarns and strands has been described in French Patent FR-A-2,607,840. This process is based on the development of a carbide layer involving a chemical reaction with the carbon of the filaments and a gaseous phase not containing any gaseous carbon compounds, thus making it possible to obtain strands exhibiting a better resistance both to oxidation and to the action of metals at high temperature. This deposition process, better known by the expression "reactive CVD" or "RCVD" (Reactive Chemical Vapor Deposition), remains limited, however, the substrate being in one-dimensional form, strands in this case.
In fact, one of the stages of this process calls for direct heating of the fibers by the application of electrical voltage. Consequently, the process and therefore the device for its implementation cannot be employed in the case of two- or three-dimensional structures such as tapes, fabrics or the like, because they would involve a high voltage and consequently would require high-powered electrical equipment, incompatible with a rational and profitable industrial plant, and which would furthermore severely jeopardize safety, especially of personnel.
The present invention is aimed at overcoming these disadvantages. It proposes a device capable of permitting the continuous treatment of fabrics or similar, that is to say of two- or three-dimensional structures, by gas phase deposition of a carbide-based passivating protective layer.